"There's only four comics properties that ever interested me in turning them into movies," Gunn told CBR. "One was We3. The others were Thunderbolts, Hit-Monkey... and Guardians of the Galaxy."

A large number of Marvel characters are licensed to studios such as Fox and Sony Pictures, but the company currently holds the rights to the majority of the Thunderbolts character roster, which includes Luke Cage, Boomerang and Man-Thing.